Martinez has missed two games due to a quad injury. He was initially scheduled to play Thursday, but was a late scratch. Martinez is hitting .327/.363/.606 over 208 at-bats.
Machado has missed four games due to a back injury. Over 258 at-bats, Machado is hitting .267/.317/.422.
Billings was designated for assignment a few days ago. He cleared through waivers and accepted an assignment to the minors.
Callaspo will play at Class A Stockton. There's a chance he will rejoin the Athletics Sunday. Callaspo is hitting .234/.308/.309 over 282 at-bats.
the team placed infielders
Uggla was signed by the Giants in recent days after the Braves released him. Uggla was hitting just .162/.241/.231 in 48 games with the Braves, and appeared in just two games with Fresno before getting the call. He is in the starting lineup for Friday's game against the Dodgers.
Abreu last appeared in the majors with the Giants last season, when he hit .268 in 52 games. He was hitting .281/.329/.434 in 64 games at Fresno.